Most importantly, the range is better with OccuSync 2.0. I use this to monitor abandoned railroad tracks. The original Mini 1 would lose video reception after about 1200 feet following the tracks, hovering low between dense trees. The new Mini 2 reaches about 40% further in this dense environment, only losing the signal after it is blocked by a concrete bridge. The range difference is most dramatic, however, while flying higher with clear line of sight, where the distance is supposed to be more than double (10km is much further than I would want to test). There are 3rd party clip-on Yagi signal boosters that may extend the range even more.
After the increased range, my next favorite new feature is the much improved remote controller. The Mini 1 has a bad design where larger phones, such as the iPhone Plus or Max series, do not fit on the mount, and the cable doesn't reach with a phone case. The Mini 2 phone mount is so much better! The antenna also functions as a spring clip so the phone sits on top in a better viewing position, and the larger phones easily fit. Another wonderful design improvement is the cable storage inside the antenna compartment, so it's easy to grab-and-go just the controller and aircraft without having to separately carry the little cable.
The controller now a return to home button, and cine / normal / sport selector switch right on the controller. This is nice as it reduces the panic when I'm trying to locate the return to home on my phone screen when someone is trying to call me on my iPhone.
The other new feature I love is the ability to do 4K video, wide-angle, 180°, and sphere panoramas (vs. 2.7K on the Mini 1). It's hair-raising to see the video results play back on the computer. It feels like cinematography quality video with a cute little thing that fits in the palm of your hand.
Looking closely at the two side-by-side, both models are identical in physical form, so the the same physical accessories designed for the Mini 1, such as the propeller guard will work on the Mini 2. I was curious about the weight difference so I weighed them on a precision lab scale. Mini 1 without battery: 5.27 oz. Mini 2 without battery: 5.56 oz. Mini 1 with battery: 8.68 oz. Mini 2 with battery: 8.37 oz. DJI made up for the slightly increased weight of the fancy new internals with a lighter battery design.
Is there anything I don't like about the updated model? Just one very minor thing -- the kit comes with a soft padded case that is similar to a camera bag or binocular bag with a shoulder strap. I much prefer the semi-hard case that came with my original Mavic Mini Fly More Combo. The gray semi-hard case looks nicer, is easier to pack in a hurry, and offers better protection. However not a big deal, as many 3rd party accessories are available.
Overall I HIGHLY RECOMMEND the Mini 2, even if you already have the original Mini. (Save some time, stop reading a million reviews, and click the BUY button). Also, this would make an amazing gift for "someone who already has everything" if they haven't tried drones before. It's super easy to fly because of the self-correcting stabilization (just before this review I accidentally hit a tree branch and it recovered itself after doing a flip, and came back home -- yay!)